<p>Adam Millard-Ball and Chris Barrington-Leigh explain trends in urban street network design.</p>

Active learning in STEM

Welcome to Science Sessions, the PNAS podcast program. Listen to brief conversations with cutting-edge researchers, Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in PNAS, plus a broad range of scientific news about discoveries that affect the world around us.